Previous research has shown that professional communities have the potential to be a powerful lever for continuous improvement in school settings. This research seeks to extend previous research by investigating the indicators of professional community that influence science teaching practice. This study took place in a network of urban neighborhood high schools, where low student achievement and high teacher turnover present barriers to professional community. Science teachers were surveyed on the extent to which they participated in a variety of formal learning opportunities and engaged in collaborative practices that are indicative of professional community over the course of a school year. The teachers also indicated the extent to which they changed their teaching practices during the same time frame. The results indicate that teachers engaged in a variety of collaborative activities such as advice seeking and collaborative discussions about curricula and student work. These conversations were associated with changes in teaching practice.